Field of the Invention
The present invention relates to a technique for achieving optical image stabilization that follows a main subject, thereby correcting an image blur.
Description of the Related Art
In recent years, along with the increase in number of the pixels of cameras and the enhancement of their performance, there has been a growing demand for a more advanced image stabilization function for moving images. For example, Japanese Patent Laid-open No. 2012-14196 proposes an image capturing apparatus that not only suppresses an image blur caused by shake of the image capturing apparatus such as camera shake, but also performs correction of an image blur by causing an optical image stabilization mechanism, which is realized with a lens, an image sensor driving mechanism, etc., to follow the main subject.
Also, Japanese Patent Laid-open No. 2007-215114 proposes not only a gyro sensor that detects only shake of an image capturing apparatus, but also a method for detecting, from an image, a motion vector that can be used for detecting the movement of the image resulting from the relative movements of the image capturing apparatus and the subject, thereby correcting image distortions including a rolling shutter (RS) distortion.
However, if an attempt is made to eliminate a blur of the main subject, the image sway and its accompanying rolling shutter (RS) distortion increase in regions other than the main subject region, such as in the background. In particular, when the subject is a moving object, the sway and the distortion are likely to be noticeable, because the relative movement of the object is greatly different from the relative movement of the background, which is stationary. If the size of a rolling shutter (RS) distortion and the size of a swaying component that cannot be eliminated by the optical image stabilization increase, it is likely that motion sickness is induced by the moving image. Furthermore, if the entire region including non-main subject regions is simply corrected based on the relative movements of the main subject and the camera, image distortions will be more considerable in the regions other than the main subject region that is the target to be followed in the image stabilization by the image capturing apparatus.